#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;
double r;
#define PI 3.1415927
int main(void){
    while(~scanf("%lf",&r)){
        double ans=4*PI*r*r*r/3;
        printf("%.3lf\n",ans);
    }
    return 0;
}
